Metal-enhanced fluorescence and excited state dynamics of carotenoids in thin polymer films.

Metal-enhanced fluorescence of carotenoids, all-trans-β-carotene and 8'-apo-β-carotene-8'-al dispersed in thin layers of polystyrene and polyethylene glycol were investigated by time-resolved fluorescence spectroscopy. The weak emission signals of carotenoids in polymer films were increased by 4-40 times in the presence of a silver island film and the emission lifetimes of both carotenoids were measured as significantly shortened. The energy transfer from the intermediate states of carotenoids to the silver islands and the subsequent surface plasmon coupled emission were proposed for the mechanisms of metal-enhanced fluorescence. The fluorescence enhancements of carotenoids in the polymer films were also investigated statistically over a wide area of the silver island films.